Evolution law of continuous dynamic recrystallization in forming of AA7075 tee valve by multi-direction loading

Abstract

In forming of AA7075 tee valve by multi-direction loading, continuous dynamic recrystallization (CDRX) will occur and significantly affect the final microstructure and performance of formed parts. In this paper, the developed physically-based internal state variable model for CDRX and finite element (FE) simulation were used to investigate the influence law of forming parameters (deformation temperature, punch fillet radius, friction factor, and the loading speed of punch) on CDRX in the intersecting region (complex deformation and possible weak zone) of the formed tee valve. By considering the grain size and its distributing uniformity in the intersecting region, the reasonable forming parameters were obtained, under which, the evolution behavior and law of the dislocation density, subgrain size, average misorientation of subgrain boundary and average grain size were revealed. The results can provide a guide for the quick prediction of CDRX and selection of the reasonable forming parameters for multi-direction loading forming of tee valves.